This section introduces aspects that may help facilitate a better understanding of the inventions. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is prior art or what is not prior art.
Optical components are sometimes integrated in a single device such as a photonic integrated circuit. Integrating optical components on semiconductor substrates using well-developed semiconductor material fabrication processes offers the opportunity to produce high yield and low cost photonic integrated circuits. For instance, various optical components such as high speed modulators, photo detectors, WDM filters, polarization rotators, polarization beam splitters, variable optical attenuators, have been monolithically integrated into single silicon substrates.